Stereotype plate



Sept 1,1936- F. A. Pos1-ER 2,052,758

STEREQTYPE PLATE v Filed Jax). 18, 1935 INVENTOR BY A MM; WVM

ORNEYS line pressure.

Patented Sept. l, 1936 l -UN.ITD 'sTTp-fs mais *l Frank ,Goss Printingr Press C V corporation of Illinois l Application ynnary 18, f 1935,` Serial@ i TheV invention Vrelates to novel and usefur-im'- provements in stereotype plates, and fmore especially to such improvements inthe parts of 'the plate that are subjected to finishing and i'n'l the -devices which cooperate toftension the plate about Vthe cylinder.` vI* f l Objects: and advantages of the'invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized. and attained by means f of the instrumentalities and combinations pointed out inthe appended claims. 1 .The invention .consists 'in thenovel parts, constructions, arrangements,- combinations and improvements herein shown and described.

. The accompanying drawing, referredzto herein and constituting a part hereof, illustrates one embodiment of the invention, and together with'the description, serves to explain the principles of the invention.

Figure 1 is a fragmentary elevation of the inner face of a plate embodying the invention;

Figure 2 is a fragmentary arcuate section through a plate; and v 'Figure 3 isa diagrammatic development ofn the back of the plate with the bevel of the ribs exaggerated. Y

An object ofthe invention is to providea stereotype plate which is designed tobe held to the cylinder by tension appliedto the' plate about the cylinder, that is,.the entire holding stress upon the plate is tensional, angularly` along the plate, and in the direction of the travel of the printing 'I'he old systems of holding` stereotype plates on the cylinder usually Iemployed clamping devices which engaged the opposed edges of the plate, usually the beveled arcuate edges, and exerted opposed, inwardly directed compression strains. Such pressure tends to buckle the plate centrally and this acts destructively in connection with the very great centrifugal strains due to high cylinder speeds. The very great printing pressures used tend to create a buckle or roll in the plate which travels along the plate ahead of the printing line. and the application of clamping pressure of the kind described on the plate edges is a further cause of disruption and plate failure. When the plates are held to the cylinder by tension applied angularly about the plate between the head edge and the tail edge, the defects and disadvantages -described are obviated. c

The present invention provides an improved plate to be tensionally held to the cylinder, the

" ".STEREPTYIE ILATE A. Foster, assignor 0m een (imam-1.11, l..

lvm-2,343: 'I plate having means for engaging with the tension exerting devices on frthe cylinder which are'powerful, simple and eilicient, and which 4are an elenient` of added strength, a very valuable feature in view' of thehlgh speeds and great printing pressures employed;A Another object of the invention isto provide a stereotype plate which has exceptional printin'gqualities'at'high speeds and under great pressure,'and which may befnished accura'tely-and expeditiouslyand so as to have its printing surface'in the true cylinder necessary to secure excellent an'd'uniform impressions. To this'end lthe-'interior ribs or projections are disposed vparallelfto the a'xis of the plate, and are finished by-being simultaneously operated on by a cutter having one or more arcuate or annular cutting edges, havingthe exact radius of the printing cylinder, and moving along the axis of theplate and of thecylinder during the finishing operieition,v while 'at'the same time the printing surfacef ofthe plate is held firmly vto the true cylindrical-form and radiusV required for the press. A machinecapacitatedlto Aso finish a plate of this kind is shown in copending application Ser. No.

744.762 filed September 20,-1934 by Charles Alonzo Thisapplication isa division of my copending applicationSer. No'. 736,816 led July 25, 1934. f *In oneiigure (Fig. 1) of the drawing a stereotype plate 1 of the one plate around typei's' shown', and in the other figure (Fig. 2) a semi-cylindrical plate, that is, `the `two Vplates around type, is shown,'a's the invention is equally applicable for one,Y two or moreplates around the cylinder. 'I'he particular` form oi tensioning devices Ahere shown areadapted'tocooperate with the form of plate tensioning devices shown in my aforesaid parent applicationSer. fNo. 736.816,"but other forms of plate tensioning devices may be employed so far as regards the main features of the invention. The printing surface 8 of the plate is cast as nearly an accurate cylindrical surface as is possible under casting conditions, and the finishing operation is designed to correct imperfections or aberrations due to or consequent upon the casting. The plate of the present invention is especially designed for a finishing process or method which is especially eilicacious in bringing the printing surface to the desired true cylindrical form. On its inner side the plate is provided with longitudinally disposed, spaced apart ribs 9, preferably extending unbrokenly the entire length of the plate from one arcuate edge to the other, the ribs being in effect elements of a cylindrical surface, and the finished surfaces of these ribs rest upon and along the plate cylinder to support the plate thereon.

The ribs are beveled slightly in cross section from their roots inwardly to the edges of the inner surfaces thereof (which surfaces after iinishing rest upon the plate cylinder), to facilitate withdrawal of the plate from the casting core. The inner surface of each rib is beveled longitudinally.Y f'rorri oneend'to theotli'erfto ifacilitate withdrawall of the plate from "the core in" the endwise direction, if that should be desired. longitudinal bevel of the rib faces is removedby the finishing operation and these inriergvfgces.- are thereby brought to truepcylinder-eiementsn b the finishing operation, as`-`s`h in^ l'ig. jl@FigsI 'l'-A of the parent applicatiorr'.find'tlfitgurellthe entire plate is shown as preferably having a very slight bevel, or increase inimdssfzsectiorrlxitthe :f axial direction to'facilitate removal ofthe plate lA' from the core, the bevel in the unnishedipoiti'ohsi betweenthe ribs beinggindicated .byV numeral. 6;. A plate o f this for-m may be iinished by pressing the printing f'surface.f igainstjga tnue ylindrical Surfacev f the proper radius. that E is.. the radius of the v perfect printing surf ace, fand passing.- i a cylindrical Cutting. and finishing tool axially with: in the plate, the cuttingtool being of-:the-same radius as the plate cylinderiof thepressandmevr mg coaxially withthe platea Sucha-,nishingopg eration fisV` effected under vthe exact. conditions Yci? rotary-printing andis effective toi-.produce :avery accurately dimensioned plate.. .fg Such Aa finishing process is described and .claimed in the beforementioned copending application Ser. No. 'l44,7 6 2 led September 20, 1934, by CharlesAlonz o Harless.. .f

In accordance withone feature ofthe inven-v tion, thelockup or tension effecting meansonthe plateaare designed to cooperate with tension means on the plate cylinder Vlocated .Wlthinthe periphery of the cylindenj Theembodied form of suchfmeans also contribute...strength;to 'the plate; where it.- 'is most needed, as they project from the plate yrather than bei-ngcut ocr depressed int- O it andV thereby decreasing v its cross sectional dimension at that point, with corresponding weakening of the platel- As embodied, therer are castwith'the plate 'lugs or;bars I0 and-I l; near the head-andtail ,straight edges of the plate, which areadapted to engageiwith plate tensioning means located within-the periphery. of the plate cylinder as already referred to; These lockup lugs are shaped and positioned'totension'rthe plate resiliently-:about the cylinderv to prevent radial displacement, to resist centrifugal stresses, and also to take up and resist the heavy tangential stresses dueto impact ofA -the printing-pressure upon the head orleadedge .of itheplat'e in fast rotary printing.

As embodied said lugs project diagonally inwardly slightly away from the adjacent straight edge of the plate, that is, they have their surfaces which engage with the tensioningV means on the plate inclined angularly somewhat off the radial line. The lugs may be formed with their surfaces slightly beveled to permit the plate to be readily removed from the casting core, and the sf are thrafterfbriight to the size and forr'nfo'r cooperating withrthecylinder tensioning devices, by the nishing operation or any suit- -able operation.

f It will-he understood that the form, proportions djother `detailslof the interior members or ele- 4 he'platefmay be varied from those herescldse tl'i'out departing from the principles f the iventlori'iand without sacrificing its chief advantages-.iff f what.; claim isz" "cylindrical stereotype plate having internally projecting,;.spacedgapart.: ribs :disposed lQngtudinally on. the interior of the plate as. elements fof; a {zylinflrical surface; said yribs.being slightly beveled; :in gcrossfsection, and also4 longitudina lly ongtheir finnerfaces, to :permit withdrawal of the plate longitudinally fromthejcore o f .a castingzmachine'and undercut devices formed pn .the .inner .surface of--the plate Vadjacent to its endstfwherebyf-plate tensioningmeans may hold the plateabollii'aicylinder. j f 1 A; cylindrical?stere'otypefplate having internally projecting, spaced apart ribs disposed elements .of Ta.; cylindrical f surface, .said ribs. on the plate ascast-.having-been beveled int-cross vsectiornnandalso longitudinally on their inner faces-,-:to.permit-withdrawal of the. plate longitudinally from-:the-core ofy a casting machine,` the inner-'faces of the ribsi havingbeen finished after casting to a true cylindrical surface to: seatthe plate on the press cylinder and1 undercutndevices formed ony the innersurface vof theplate adjacent tdfits ends Wherebvplate tensioningfmeans may holdthe plateabout a cylinder. 1 f .-2' L 3. A cylindrical stereotype ,platefhaving an internal surface for surfaces, suclras; longitudinally disposed; spaced apart ribs, adapted tto. seat Yon' the surface of a plate cylinder, and having 'a lookup. lug'f disposed. longitudinally near 1 the leading end-ioff the iplate,l and projecting' inwardly fartherrtharr-the seating surface'of theV plate,the lookup-bar being undercut or projecting diagonallyto engagedevices .onfthe plate cylinder'topre-v vent radialdisplacement offthe'plateand to preventfbackward displacement-ofthe plate around the'cylindenpfi- 

